Suction dredger having plural pumps and plural articulated pipe sections

ABSTRACT

Suction dredger for sucking up a particulate material such as sand. A suction pipe is inserted into a body of sand below the bottom of a body of water to withdraw water-sand suspension having a desired concentration of sand in such suspension. At the lower end of the pipe, the sand is drawn in at very high concentration and at some level above this point water is separately introduced so that a desired concentration is obtained. The suction pipe consists of at least two pipe parts swingably connected to each other. The maximum suction output of the submerged pump is obtained by swinging the frame supporting the pump into a vertical position.

United States Patent De Koning et a].

[ 1 SUCTION DREDGER HAVING PLURAL PUMPS AND PLURAL ARTICULATED PIPESECTIONS [72] inventors: Jan De Koning, Amsterdam; Tjako AaldrikWalters, Utrecht, both of Netherlands [73] Assignee: N.V.Ingenkursbureau voor Systems en Octrooien Spanstaal", Rotterdam,Netherlands 22 Filed: Nov. 17, 1969 21 Appl. No.: 877,141

[30] Foreign Application Priority Data 3,407,520 10/1968 Donkers ..37/58til [451 Aug. 8, 1972 FOREIGN PATENTS OR APPLICATIONS 6,501,405 8/1966Netherlands ..37/58 980,549 1/1965 Great Britain ..37/58 3 l .04110/1933 Netherlands ..37/58 Primary Examiner-Robert E. Pulfrey AssistantExaminer-Clifford D. Crowder Attorney-Imirie, Smiley, Snyder and ButrumABSTRACT Suction dredger for sucking up a particulate material such assand. A suction pipe is inserted into a body of sand below the bottom ofa body of water to withdraw water-sand suspension having a desiredconcentration of sand in such suspension. At the lower end of the pipe,the sand is drawn in at very high concentration and at some level abovethis point water is separately introduced so that a desiredconcentration is obtained. The suction pipe consists of at least twopipe parts swingably connected to each other. The maximum suction outputof the submerged pump is obtained by swinging the frame supporting thepump into a vertical position.

4 Claim, 3 Drawing Figures PATENTED M1 8 I972 SHEET 10F 2 TJ'AKO A. WLTERS PATENTEDAUB 8:912 3.681.862 sum 2 c; 2

INVENTORS JAN 62 KoNiNG TJAKO A. WdLTERs BY M MQ, Mama ATTK m wasSUCTION DREDGER HAVING PLURAL PUMPS AND PLURAL ARTICULATED PIPE SECTIONSThe invention relates to an improvement of a suction dredger comprisinga pump and a suction pipe which is connected to said pump and which hasat least one first nozzle for spoil at its lower end and at least onesecond nozzle mainly for water between the pump and said lower end,wherein said pump is mounted on a frame movably suspended from a shipsbody which is lowerable and liftable together with said pump relativelyto said ships body, at least said first suction nozzle being arranged atan end part of said suction pipe.

Such a suction dredger is known.

In said known suction dredger said end part of said suction pipe ismovably connected with said frame supporting said submerged pump.However, in said known suction dredger this pump cannot always bepositioned at its maximum depth, at which maximum depth the pump has itsgreatest suction output, owing to the end part of the suction pipe beingjammed in solid ground, for instance solid mud or clay covering thespoil or sand to be sucked up.

The invention has the object to provide a suction dredger in which thisdrawback is avoided.

The invention provides a suction dredger of the kind mentioned above,wherein said end part of the suction pipe communicates with an inletpart of said pump by means of an intermediate part of said suction pipewhich is swingably connected to said inlet part as well as to said endpart.

Preferably the intermediate part of the suction pipe consists of atleast two parts swingably connected to each other.

The invention further has the object to provide a method of suctiondredging particulate material below the bottom of a body of water, whichcomprises the steps of:

inserting the lower end of a suction pipe into a body of the materialbelow the level of the bottom of a body of water,

communicating the suction pipe with a submerged suction pump to withdrawthe particulate material through the lower end of the pipe comminglingwater with the particulate material at a point along the length of thepipe which is spaced above the lower end thereof,

measuring the concentration of particulate material in the particulatematerial-water mixture being withdrawn through the pipe above said pointat which the particulate material and water are commingled,

maintaining the concentration of particulate material in the particulatematerial-water mixture within predetennined limits,

and adjusting the level of said submerged suction pump independent fromthe position of the lower end of the pipe.

Preferably the pump is maintained at its maximum depth.

The above mentioned and other features of the invention will beillucidated in the following description with reference to theaccompanying drawings, wherein:

FIG. 1 is a preferred suction dredger according to the invention,

FIG. 2 is another preferred suction dredger according to the inventionand FIG. 3 is a part of the suction dredger of FIG. 2.

The suction dredger according to the invention of FIG. 1 comprises aship's body 1, a lowerable and liftable supporting frame 26 swingablymounted about a horizontal axis 25 on the ships body 1, a pump 3 fixedto said frame 26. The discharge pipe 2 of said pump 3 is swingablyconnected to the inlet pipe 44 of a pump 28 mounted in the ships body I.The discharge pipe 2 is swingably connected about said axis 25. Thepressure side of the pump 28 communicates with a conveying pressure line1 l.

The inlet pipe 27 of the pump 3 communicates through a flexible conduit29 with an intermediate part 4 of the suction pipe 30, which in turncommunicates through a flexible conduit 31 with an end part 24 of thesuction pipe 30. The intermediate part 4 is swingably connected to theinlet pipe 27 and the end part 24 by means of pivot hinges 32 and 33.

The frame 26 and the suction pipe 30 are suspended from the ships body Iby means of winches l0 and 8, 9 and cables 7 and 5, 6 for adjustablylifting and lowering them.

The lower end of the end part 24 has a first suction nozzle 22 forsucking in mainly spoil 34 surrounding said lower end and beingfluidized. This lower end is covered by a cage 21.

A second suction nozzle 15 for taking in mainly water is provided in theintermediate part 4, the quantity of water taken in being adjustable byadjusting the flow area of suction nozzle 15 by means of a slideremotely controlled from the ships body for controlling theconcentration of spoil in the spoil-water mixture sucked up by the pump3. The value of this concentration is measured by means of aconcentration sensitive pick up 45 incorporated in the intermediate part4.

In the method according to the invention the pump 3 is submerged at themaximum depth obtained by lowering the frame 2 into the vertical orsubstantially vertical position, in order to use the maximum suctionoutput of this pump 3. [t can be positioned at its maximum depthcorresponding with vertical position of frame 26 independently from theposition of the end part 24, 24'. FIG. I shows that the end part 24 ofthe suction pipe is jammed in a narrow gap 13 of solid ground 18.

The suction dredger of FIGS. 2 and 3 corresponds with that of FIG. 1with the exception that the intermediate part 4 consists of two parts 40and 4b instead of one rigid part, and that the second suction nozzle 15is provided in the end part 24 in a particular way instead of in theintermediate part 4.

The intermediate parts 4a and 4b communicate with each other through aflexible conduit 37 and are swingably connected to each other by meansof a pivot hinge 33. The intermediate parts 40 and 4b are suspended fromthe ships body 1 by means of winches 9a and 9b and cables 6a and 6b.

The end part 24 (FIG. 2) consists of an inner tube 23 communicating withthe intermediate part 4, a pipe 16 telescopically slidable relatively tothe inner pipe 23 by means of a remotely adjustable hydraulic jack 38and of a jacket 17 surrounding the inner pipe 23 and the slidable pipe16, and being connected to the inner pipe 23. The jacket 17 is providedwith water inlets 39 at its upper end and with a first suction nozzle 22for spoil at its lower end. Water 40 entering the jacket 17 throughinlets 39 flows between jacket 17 and pipes 23 and 16 downwards andenters the slidable pipe 16 through a periphery gap between jacket 17and the lower edge of slidable pipe 16, said gap forming the secondsuction nozzle for water. This water and the spoil entering the jacket17 through the first suction nozzle 22 forms a water-spoil-mixturesucked up by pump 3. The lower edge of the slidable pipe 16 is kept inthe vicinity of the level to which the spoil enters the jacket owing tosuction of pump 3 and owing to the pressure available in the fluidizedspoil 42 at the outside of the suction pipe 30. in the method accordingto the invention this pressure is picked up by means of pressuresensitive pick up 20. For controlling the concentration of spoil in thewater-spoil-mixture the distance between the first suction nozzle 22 andthe second suction nozzle 15 or the lower end of slidable pipe 16 isadjusted in dependence on the pressure picked up by means of pick up orin dependence on the measured value of the concentration picked up bymeans of above mentioned concentration sensitive pick up 45.. Thisdistance is adjusted by means of hydraulic jack 38. The pressure pickedup by pick up 20 is about equal to the sum of the weights of spoilcolumn l-l, and water column [-l,,.

Since the cost price of the suction dredger increases sharply with thelength of the supporting frame 26, and it is important that the pump 3should be adapted to be mounted at the maximum depth, it is a greatadvantage of the suction dredger according to the invention that thesupporting frame 26 can be disposed vertically or substantiallyvertically irrespective of the position of the end part 24.

What we claim is:

1. A suction dredger assembly comprising in combination:

a dredger vessel and a first pump mounted on said vessel, said firstpump having an inlet for receiving a suspension of dredging spoil inwater and an outlet for discharging such suspension;

frame means carried by said vessel and a second pump mounted on saidframe means, said second pump having an inlet and having an outletconnected to the inlet of said first pump about a substantiallyhorizontal pivot axis located remote from said inlet of the second pump;

means for raising and lowering said frame means relative to said vesselabout said pivot axis whereby the inlet of said second pump may bedisposed at a desired depth within the body of water supporting saidvessel;

suction pipe means connected to the inlet of said second pump forinducting dredger spoil and forming a suspension thereof in water whichis delivered to said second pump, said suction pipe means comprising arigid free end section adapted to be inserted deeply into an underwaterbody of dredger spoil and an intermediate section extending between saidend section above the level of dredger spoil and the inlet of saidsecond pump, said intermediate section being swingably connected both tosaid end section and to the inlet of said second pump whereby said framemeans may be lowered at least substantially to its maximum depth withoutrequiring movement of said end section.

2. A suction dredger assembly as defined in claim 1 wherein saidintermediatesecg It comprises a pair of suction pipe sections swlnga yconnected to each other.

3. A suction dredger assembly as defined in claim 2 wherein said suctionpipe means presents a first suction nozzle at the free end of said endsection and a second suction nozzle within said end section inselectively spaced relation to said first suction nozzle to effect saidformation of suspension.

4. A suction dredger assembly as defined in claim 1 wherein said suctionpipe means presents a first suction nozzle at the free end of said endsection and a second suction noule within said end section inselectively spaced relation to said first suction nozzle to effect saidformation of suspension.

UNI'IED STATES PATEN'I OFFICE CERIIFICA'IE 0F CORRECTION Patent No. 3 I681 I 852 Dated Aug 8, 1972 lnventofls) Ian de Koning and Tjako AaldrikWolters It is certified that error appears in the above-identifiedpatent and that said Letters Patent are hereby corrected as shown below:

In the assignee's name "Systems" should be Systemen Signed and sealedthis 9th day of January 1973.

[SEAL] Attest:

EDWARD M.FI.,ETCIIIZR,JR. ROBERT (IOT'ISCHALK Attesting OfficerCommissioner of Patents FORM PO-OSO (10-69] USCOMWDC eoawhpfig w u soovznnmzm murmur, ornc: lava o-ass-au

1. A suction dredger assembly comprising in combination: a dredger vessel and a first pump mounted on said vessel, said first pump having an inlet for receiving a suspension of dredging spoil in water and an outlet for discharging such suspension; frame means carried by said vessel and a second pump mounted on said frame means, said second pump having an inlet and having an outlet connected to the inlet of said first pump about a substantially horizontal pivot axis located remote from said inlet of the second pump; means for raising and lowering said frame means relative to said vessel about said pivot axis whereby the inlet of said second pump may be disposed at a desired depth within the body of water supporting said vessel; suction pipe means connected to the inlet of said second pump for inducting dredger spoil and forming a suspension thereof in water which is delivered to said second pump, said suction pipe means comprising a rigid free end section adapted to be inserted deeply into an underwater body of dredger spoil and an intermediate section extending between said end section above the level of dredger spoil and the inlet of said second pump, said intermediate section being swingably connected both to said end section and to the inlet of said second pump whereby said frame means may be lowered at least substantially to its maximum depth without requiring movement of said end section.
 2. A suction dredger assembly as defined in claim 1 wherein said intermediate section comprises a pair of suction pipe sections swingably connected to each other.
 3. A suction dredger assembly as defined in claim 2 wherein said suction pipe means presents a first suction nozzle at the free end of said end section and a second suction nozzle within said end section in selectively spaced relation to said first suction nozzle to effect said formation of suspension.
 4. A suction dredger assembly as defined in claim 1 wherein said suction pipe means presents a first suction nozzle at the free end of said end section and a second suction nozzle within said end section in selectively spaced relation to said first suction nozzle to effect said formation of suspension. 